This invention relates generally to the field of storage RAID controllers and Storage Area Network (SAN) systems. As ever-increasing demand for more data hence, for more data storage, SAN and RAID technologies available today have failed to meet performance requirements and with prohibitively high cost made them out of reach for the majority of the small and some medium size businesses.
A majority of small and some medium size businesses and corporations, recognizing the productivity gains resulting from high-performance and high availability computing systems are often unable to acquire suchlike systems due to prohibitively high cost of data storage subsystems. To reduce the cost they often utilize large number of disjoint individual servers where each server is dedicated to one or more specific applications, such as mail servers, accounting application server, etc. This environment, clearly, leads to underutilized available aggregate computing power of all servers since each server is dedicated to specific application and the workload cannot be shared. This approach introduces other issues such as system and network administration, fault tolerance, fragmented data storage, data storage and backup management problems, as well as system complexity, and so forth. Data access and data sharing could be done at different levels such as at block level (shared block storage), multiple hosts accessing the same disk drives or Logical Unit Numbers (LUNs), or at the file level using file systems like Network File System, Common Internet File System, etc.
A Network File System (NFS) is a client/server application that facilitates viewing and optionally storing and updating files stored on a remote computer (often called a file server). The client system, which may be a work station or cluster node, has to run NFS client and the other computer, file server, needs the NFS server software. Both computers typically must have networking protocol software such as Transmission Control Protocol/Internet Protocol (TCP/IP) and networking hardware such as Ethernet, InfiniBand, Myrinet, or other Network Interface Cards (NICs) installed, since the NFS server and NFS client use network protocols to exchange the files data. This approach leads to a bandwidth bottleneck on both client and file server sides, mainly, due to NFS protocol overhead, limited Peripheral Component Interconnect (PCI) bus data rate, and possibly high latency associated with traditional architecture of the data storage subsystem attached to it.
A protocol standard developed by Microsoft, Common Internet File System (CIFS), which allows programs to make requests for files and services located on a remote computer, facilitates the same basic function as previously mentioned NFS. CIFS is typically utilized in Microsoft operating system environments to allow shared access from one computer to files stored on another remote computer within the same network. A CIFS client makes a request to a CIFS server (usually in another computer) for a file access or to pass a message. The server executes requested action and returns a response. CIFS is a public version of the Server Message Bock (SMB) protocol. The file server running CIFS suffers from the same problems as earlier mentioned NFS server because, this is in essence the same or similar hardware and technology.
TCP/IP protocol overhead together with network latency affects the performance of NFS/CIFS subsystems by significantly increasing access delays for network-attached disk when compared to locally attached disk. However, locally attached disk performance, usually, is much lower compared to data storage subsystem implementations such as RAID or Storage Area Network (SAN) subsystem. Traditional SAN design and implementation even though in many cases superior to locally attached disk drives, underutilize aggregate data rate potential of all attached disk drives by making use of time division multiplexing over typically small number of I/O (network) links between servers and the SAN subsystem attached to it.